A photovoltaic device (photovoltaic module) has been proposed in which a plurality of solar cells (power generation elements) and a metal line that electrically connects the solar cells together are bonded on a metal plate with a resin insulating layer therebetween (refer to PTL 1). In this device, most of the surface of the metal line is exposed without being covered with an insulating layer.
In addition, a photovoltaic unit (photovoltaic module) has been proposed in which a solar cell element (power generation element) and a metal line for extracting a current generated in the solar cell element are mounted on a metal base substrate with an insulating layer therebetween (refer to PTL 2). In this unit, a part of the surface of the metal line is covered with an insulating layer, the part being other than a part to which a wire or the like is connected from the outside. The base substrate is fixed to a solar-cell-mounting substrate composed of a metal.